Clamping jaw



June 9, 1959 R. A. LALLl 2,889,865

CLAMPING JAw Filed April 2, 1956 2 Sheets-Sheei 1 L A- 7 V//////A/////7A 29 INVENTOR. 31 l .9! Romea A. Lalh 36 364 35 7 35d BY ATTORNEYSR. A. LALLI CLAMPING JAW June 9, 1959 2 Sheets-Sheet 2 Filed April 2,1956 INVENTOR. Romeo A. la ZZL' United States CLAMPING JAW Romeo A.Lalli, Bridgeport, Conn. Application April 2, 1956, Serial No. 575,470

2 Claims. (Cl. 153-48) This invention relates to a stretch press andmore particularly to a stretch press having an improved clamping meansfor securing the marginal edge portions of a sheet metal material duringthe stretching or forming operation.

In shaping magnesium and titanium sheet material or the like, such asare used in the formation of skin surfaces of an airplane, helicopter orthe like, it has been discovered that a practical way of shaping suchsheets into the desired form is by a stretching operation. Heretofore,the stretching operations have been performed by disposing a blank ofsheet material between a pair of clamping means and forcibly moving aparticular forming die or block into engagement with the materialsecured between the clamps so that the material is stretched to assumepermanently the shape of the forming die. However, in the past, for eachforming die having differently shaped die surfaces, a particular pair ofclamps was required to be used in conjunction therewith in order toproperly shape the desired form. Consequently, the clamping meansutilized with one forming die could not be adapted or used with a secondforming die for shaping a differently shaped component part of anairplane or the like.

In order to overcome the disadvantage of requiring a special pair ofclamping means for each forming die required to make up each of thecomponent shapes, there is provided according to this invention astretch press having a universal clamping means which is adapted to beused in conjunction with any of a plurality of differently shapedforming dies, thereby eliminating the need of the specialized clampingmeans heretofore required for each particular forming die.

An object of this invention is to provide a stretch press with auniversal clamping means for anchoring the marginal portions of a sheetmaterial in a predeterminate, complementary, cooperative relationshipwith a forming die which is adapted to be forcibly moved against thematerial to permanently shape the material into a form having irregularcurvatures orcontours corresponding to that of the forming die.

Another object of this invention is to provide a stretch press with abank of relatively narrow individually operated clamping jaws which aremovable relative to each other andto the forming-die 0f the press forsecuring the marginal edge portions of a sheet material disposed oversaid die, whereby the jaws are individually positioned in a of theindividual clamping jaws comprising the bank with I novel clamping meansfor gripping the sheets and holding them securely while the stretchingpressures are applied and with means for accelerating the opening andclosing movement of the jaw members.

I The objects of this invention are accomplished by a i an airplane,helicopter or the like.

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stretch press having a forming die over which a sheet material isstretched until the material permanently assumes the shape of the die.Disposed on opposite sides of the forming die are improved clampingmeans for securing the marginal edge portions of the said material in amanner to simulate the approximate curvature complementing that of theforming surface of the die to facilitate stretching the material intothe desired form as the forming die is moved relative to the clampingmeans. According to this invention, the clamping means are universallymounted on the frame to assume any predeterminate contour to conform toany of a plurality of forming dies, each having a different contour orshape. This: is accomplished by universally mounting the improvedclamping means so that it can be arranged to simulate any of a number ofdiffering marginal contours depending upon the particular shape offorming die to be used. Accordingly, each clamping means comprises abank of a plurality of relatively narrow, individually operated,clamping jaw units which are movable relative to each other and to theforming die. Each bank of jaw units is rotatably and pivotally mountedas a whole about a perpendicularly disposed axis, and is also adaptedfor movement relative to the forming die. Further, each clamping jawunit in the bank is individually rotatable and transversely adjustablerelative to each other. As a result, the individual clamping. jaw unitsin the bank, within a given range, can be adjusted in space to simulatethe approximate curvature complementing that of the forming die.Furthermore, each of the individual jaw units are provided with novelcam means for accelerating the opening and closing of the individual jawmembers by a simple manual movement.

A feature of this invention resides in the provision of a novel clampmeans comprising a plurality of individually operated jaw units whichmeans is rotatably and pivotally mounted as a whole about axes which areperpendicularly disposed relative to each other.

Another feature of this invention resides in the provision whereby theindividual clamping jaw units com prising the clamping means areindividually and inde pendently rotatable and transversely adjustablerelative to each other.

Another feature of this invention resides in. means whereby the openingand closing of the jaw members of each unit is accelerated by simplerotary action exerted on the actuating means of each individual clampingjaw.

Other features and advantages will be apparent from the specificationand claims when considered in connection with the drawings in which:

Figure 1 is a front elevational view of a stretch press according tothis invention.

Fig.2 is an end view illustrating a bank vof clamping aws.

Fig. 3 is a top view of the clamping bank as viewed from Fig. 2.

Fig. 4 is a side view of an individual clamping jaw;

Fig. 5 is an enlarged detail view partly shown in sec-: tion of theclamping jaw.

Fig. 6 is an enlarged detail front view partly shown in section of theclamping jaw.

Referring to Fig. 1, there is shown an improved stretching press forshaping unformed or partially formed sheets of magnesium, titanium orthe like into shapes such as might be used in forming the component skinsections of According to this invention, the press 10 consists of asupporting frame A, a forming die B mounted thereon and a pair-ofimproved clamping means C disposed on either side of the forming die andadapted to be secured to the marginal edge.

portion of a material 11 disposed over the die so that upon relativemovement of the die and clamping means the material will be stretched tothe desired shape. While the clamping means can be moved relative to afixed die member in order to produce the relative movement therebetween,in the herein illustrated form of the invention, the clamping means isrelatively fixed and the die is movable.

As "illustrated in Figs. 1 and 2, the frame A consists of a pair ofchannel members '12 supported in spaced back to-back relationshipwherein 'theflange portions 13 thereof are outwardly turned to form aguide rail for the clamping means as will be hereinafter described.Intermediate the ends .of the frame, there is supported the forming dieB which has its upper face provided with the desired shape which isadaptedto be forcibly moved by any suitable power means, as for examplepiston and cylinder means 14 actuated by'hydraulic pressure or the like,'into engagement with the sheet material 11 disposed thereover and heldin position by the clamping means C so that the sheet will permanentlyassume the shape of the die. While the die is herein illustrated ashaving both a transverse and longitudinal curved surface to form anarticle having a corresponding compound curvatureor contour, it will beunderstood that the forming die may be shaped to have any desiredcurvature or contour as might be required by the individual requirementsof the skin components necessaryto make up a fuselage section or thelike of an airplane, helicopter and the like.

To eliminate the necessity of utilizing a particular or specializedclamping means for each of several of the variously shaped forming dieswhich may be required to make up the particular sections necessary, animproved clamping means C is provided whereby the clamping means can beadjusted and utilized in conjunction with any of the variously shapedforming dies which might be required to form the various componentsections .of an airplane and the like.

As illustrated in Fig. l, the clamping means C are disposed on eitherside of the forming die. While the clamping means may be both fixed tothe frame or one fixed and the other rendered movable thereto, theclamping means are herein illustrated as being both movably mounted onthe frame relative to each other so that they can be both adjustablypositioned relative to the forming die as may be required by aparticular "form to beshaped. Since the clamping means disposed oneither side of the die are essentially alike, but opposite inconstruction, it is considered that for purposes of explanation, thedescription of one is sufl'icient.

According to this invention, the clamping means C includesa bank 15 ofrelatively narrow, individually .operated clamping jaw units pivotallyand rotatably mounted on a carriage 16, the latter being slidablymountedon the upper flanges 13 of the channel members whereby the carriage 16is adapted to be longitudinally moved along the frame to carry the bankof jaw units into the desired adjusted position relative to the formingdie. While the adjustment of the carriage 16 along the frameisaccomplished manually, it is herein illustrated as being mova ble by ascrew 17 mounted in a brace 18 disposed between the channel members 12adjacent the end of the frame, the screw 17 being threaded to a nutmember 19 fixed to and depending from carriage 16. A hand wheel 20 ismounted to the outer end of the screw, so that by simply rotating thewheel in either direction causes the carriage to be longitudinally movedalong the frame.

Referring to Fig. 2, the carriage '16 comprises atop and bottom plate 21and 22 respectively, the latter being provided with depending brackets23 to form agroove for receiving the rail flanges 13 of the channelmembers on which the carriage is slidably mounted and .guided intoadjusted position. Securing means in the form of set screws 24 may beprovided to fix the carriage '16 in adjusted position along the frame.

In order that the bank 15 of clamping jaw units may be angularlydisposed about avertical axis relativeto'the forming die in the eventthe-shape to be formed thereby so requires, the upper or top plate 21 ispivotally mounted by a central pivot bolt 25 to the bottom plate 22whereby the top plate 21 is rotatably positioned relative to the bottomplate 22. To lock the plates 21 and 22 in adjusted position withrelation to each other, the upper plate 21 is provided with a,-pair.ofoppositely disposed arcuate slots 26 for receiving'locking bolts 27threaded into the bottom plate 22.

Connected to .the upper plate 21 and projecting upwardly therefrom is apair of opposed bracket members 28 to which a base plate29 forsupportingthe individual clamping jaw units 30 is pivotally connected. Referringto Figs. 2 and 3, the base plate 29 consists of an elongate plate 31having a dependent web 31a located in and secured to a pair of dependinglugs 32 by which it is pivotally supported on the brackets 28 by meansof pins .33. The base plate 29 is further provided with a plurality ofspaced, transversely extending, inverted T-slots 34 .in which theindividual clamping jaw units 30, as will be hereinafter described, aremounted to form the bank of clamping jaw units, which jaw units areadapted to be shiftably mounted, transversely of the base plate so as toassume any adjusted or staggered-position relative to each other."Therefore, as shown in Fig. 3, the clamping jaw units 30 can beadjusted to have a curvature corresponding to that curvature of theforming die. Further, since the base plate 29 is pivoted to the carriage16 by means of pins '33, 'it will be noted that the bank as a whole canbe pivoted toward or away from the die as may be desired.

According to the-present invention, the base plate has mounted thereon aplurality of improved individually operated clamping jaw units 30. Theindividual units include an L-shaped base portion 35 having the base leg35a slidably and pivotally mounted to the base plate 29 for renderingthe unit transversely adjustable along its respective slot 34. A stud 36projecting upwardly through the slot secures the base portion 35 of theunit to the base plate, the head 36:: of the stud being retained in theT-slot. The upwardly extending leg portion 35b of the base portion 35 isprovided with a transversely extending bore for receiving a pin 37aboutwhich a jaw member 38 is pivoted so that it may be tilted with respectto the base plate 29 as may be required, the upper portion of thejawmember being provided with a gripping portion 38a. Secured to the jawmember by suitable fasteners 39 is a bracket 40 which is provided with arecessed portion 41, the recessed portion being adapted to be positionedopposite the gripping portion 38a of the jaw member. Mounted in therecess 41 of the bracket is a second or normally retracted, movablymounted clamping jaw member 42 which is adapted to be moved relative tothe fixed jaw member 38. This is accomplished by supporting the movablejaw member 42 on the bracket 40 by a plurality of pin members 43 whichare slidably mounted in transversely extending bores 44, a portion ofeach bore 44 being enlarged to accommodate a coil spring 45 whichnormally tends to urge the pin members 43 and attached jaw member 42into retracted position within the recess, as shown in Fig. 5. Ifdesired, the base of the movable jaw member 42 may be provided withserrations 42a to securely grip the material disposed between the jawmembers.

According to this invention, each clamping jaw'uni-t 30 arranged in thebank is provided with an individual operating means by which the jawscan be individually operated by a simple manual operation. As shown inthe drawings, the means for operating the movable jaws comprises a shaft49 mounted in a transverse .bore in the bracket 40 and having aneccentric camming portion 49b thereon which engages adowel or roller 47disposed in apassage 46, while roller 47 engages a recess 42!) in theback of the movable jaw. Shaft 49 is rotatably mounted on the bracket 40in a transversely extending bore, the ends 49a of the shaft being inbearing relationship in the bore of the bracket. The eccentric cammingportion 49b engages the roller 47 so that upon rotation of the shaft 49,the eccentricity of the intermediate portion 49b of the shaft displacesthe roller 47 laterally, thereby advancing the jaw member 42 intoclamping position.

To facilitate rotation of the shaft 49, a manual operator 50 isprovided. As illustrated in Figs. 2 and 4 to 6, the operator comprises arod 51 having a knob 52 fixed to the upper end thereof, the rod 51 beingconnected to the shaft 49 intermediate the ends thereof. As illustratedin Figs. 2 and 5, the bracket 40 is provided with a slot 53 toaccommodate for rotation of the handle for clamping and unclamping thejaw members.

In order that the movable jaw member 42 may be accelerated to itsclamping and unclamping position upon actuation of the actuating means50, the eccentric cam portion 49b of the shaft is provided with alongitudinally extending recess 49c which is adapted to receive theroller 47. Therefore, with reference to Fig. 5, it will be noted that innormal, open jaw position the roller 47 is in the recess 42b of the jawmember and recess 490 of the cam. Thus, as the handle 50 is rotated,counterclockwise as viewed in Fig. 5, the shaft is rotatedcounterclockwise causing the camming surfaces 49d of the eccentriccamming portion 49b to engage the roller 47 to quickly cam or displacethe roller 47 laterally and to the right to move the clamping jaw 42into clamping position onto the marginal portion of a sheet materialdisposed between the jaw members. Because of the roller being normallyseated in the recess 490, it will be noted that maximum lateraldisplacement occurs during the initial rotation of the handle wherebythe roller 47 is forced out of the recess 490 to move the movable jawmember into clamping position. Continued rotation of the shaft 49 causesthe outer camming surface 49d of the shaft to wedge the roller againstthe movable jaw member to lock the same in clamped position. Conversely,it will be noted that in unclamping the sheet, the shaft 49 is rotatedclockwise from clamped position to the position illustrated in Fig. 5.As a result, the gripping action is gradually released until the instantthe recess 490 is aligned with the roller 47, whereupon the latter isquickly snapped into seated position due to the action of the springs 45normally biasing the jaw member 42 to open position. Consequently, itwill be noted that the accelerated feature of the novel clamping jawherein described greatly reduces the amount of time involved in openingand closing of the clamping jaw units 30. Further, the clamping means ofthis invention comprises relatively few parts which greatly reduces thecost of manufacture and material, yet being sufiiciently strong toresist the forces applied for stretching the material secured thereby.Furthermore, it will be noted that the movable clamping jaw units areeasily and readily operated between the clamped or unclamped position bya simple rotary movement of the shaft.

Also, since relatively narrow jaw units are employed and are universallyadjustable on the clamping means, they may be positioned to assume anydesired predetermined setting to conform to that contour to be formed bythe forming die. Because of this important feature, the marginal edgeportions of the sheet material can be reduced to a minimum and cancorrespond more accurately to the curvature to be formed by the dieproper, thereby substantially reducing the amount of material requiredto be trimmed from the finished article formed thereby. Further, theneed of specialized clamps for each differently shaped die iseliminated; consequently, a press having a universal type clamp asherein described can be utilized in conjunction with any of thevariously shaped dies required.

Variations and-modifications may be made within the scope of the claimsand portions of the improvements may be used without others.

I claim:

1. For use in a stretch press for shaping an article of manufacture,said press having a frame, a forming die for shaping articles havingirregular contours, said frame and die being relatively movable forstretching a sheet of unformed or partially formed sheet metal disposedover said die for assuming permanently the shape thereof, and a carriageslidably mounted on said frame for longitudinal adjustment relativethereto; clamping means adapted to be mounted on said carriage forgripping the edge portion of said sheet during the stretching operation,said clamping means including a base plate adapted to be pivotallymounted on said carriage, said base plate having a plurality of spacedslots, a bank of individually operated relatively narrow clamping jawunits mounted on said base plate, said jaw units each having a baseportion rotatably mounted on said base plate and slidably mounted insaid slots for movement therein, a jaw member pivoted to said baseportion, a bracket connected to said jaw member, a second jaw membermovably mounted on said bracket and adapted to be moved relative to saidother jaw member, spring means normally urging said second jaw memberaway from said I'll'SL mentioned jaw member to maintain said jaw membersnormally spaced, and means for moving said second jaw member against theforce of said spring means and toward said first mentioned jaw member,said moving means including a roller mounted on said backet inengagement with the movable jaw member, and a cam means including aneccentric cam member having a shaft mounted for rotation in said bracketin fixed relation to said first jaw member and having a portion forminga recess and being in camming engagement with said roller, said recessnormally forming a seat for said roller in normal open jaw position, andmeans including an individually operated handle connected to said shaftfor rotating said eccentric member to earn said roller in and out ofsaid recess for accelerating lateral displacement of said roller andengaging jaw member relative to said other jaw member to clamp andunclamp the sheet therebetween, said jaw units being adapted to beindividually positioned relative to each other along said base plate toconform the contour edge to be formed so that the desired contours ofthe sheet can be maintained adjacent the edge portions thereof therebysubstantially reducing the amount of metal required to be trimmed alongthe edge portions of the finished article.

2. In a clamping means to be mounted on a stretch press including apivotally mounted base plate having a plurality of spaced slots therein;a clamping jaw unit comprising a jaw member, a bracket mounted on saidjaw member, a second jaw member movably mounted on said bracket, saidmovable jaw member being adapted to be moved relative to other said jawmember, means for moving second said jaw member, said means including adowel mounted on said bracket in engagement with the movable member, ashaft rotatably mounted on said bracket in fixed relation to said firstjaw member and having a portion forming cam means in camming engagementwith said dowel means for laterally displacing said dowel means andengaging jaw member relative to said other jaw member upon rotation ofsaid shaft for clamping and unclamping an article therebetween and abase portion pivotally connected to said first jaw member, said baseportion being adapted to slidably engage one of said slots in said baseplate whereby-on engaging the material to be stretched in said clampingmeans and stretching the same-said jaw unit adjusts itself to thechanging conformation of the material.

(References on following page) 7" 8 :ReferencesCited in=:the;fi1eof"thispatent 2;609;860 =Kindelberger Sapt. 9, :195'2 UNITED STATES :PA'PENTSM2692j633 Grsen .0613. 26, 11954 1,683,906 M honey S pt-11,1 2 1,732,445Lapointe. Oct.22, 1929 5 y 1,781,180 .Jarecki Nov. 11, 1930 v 1,944,603Hacker Jan.23,-1934 FOREIGN PATENTS 2,269,549 Oeckl Jan. v13, 1942112,321 Sweden NOV. 7, 7-1944

